Add docs for example of gRPC health check success codes

[ugwis]

Issue

none

Description

Add the gRPC status code to the document as health check success codes.

+ - use gRPC single value + ``` + alb.ingress.kubernetes.io/success-codes: '0' + ``` + - use gRPC multiple value + ``` + alb.ingress.kubernetes.io/success-codes: 0,1 + ``` + - use gRPC range of value + ``` + alb.ingress.kubernetes.io/success-codes: 0-5 + ``` 

See also the Matcher Data Type for possible gRPC status code values.
https://docs.aws.amazon.com/elasticloadbalancing/latest/APIReference/API_Matcher.html

aws-load-balancer-controller currently supports gRPC target group and ALB can checks grpc-status with health check.

aws-load-balancer-controller/pkg/ingress/model_build_target_group.go

Lines 386 to 394 in 9c79e45

	_ = t.annotationParser.ParseStringAnnotation(annotations.IngressSuffixSuccessCodes, &rawHealthCheckMatcherHTTPCode, svcAndIngAnnotations)
	if tgProtocolVersion == elbv2model.ProtocolVersionGRPC {
	return elbv2model.HealthCheckMatcher{
	GRPCCode: &rawHealthCheckMatcherHTTPCode,
	}
	}
	return elbv2model.HealthCheckMatcher{
	HTTPCode: &rawHealthCheckMatcherHTTPCode,
	}

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the docs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: ugwis / name: Yuta Kitamura (7a16b71)

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[kishorj]

/lgtm

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